Adding a timout command when running the executable file could cause wrong coverage result

[cicilzx]

I'm not sure it is a bug or my incorrect behaviour.
Here is what I did:

1. A simple Rust code:

fn main() {}

2. Build, run, and get coverage information:

rustc -C instrument-coverage file.rs
./file
grcov . --binary-path ./file -s ./file.rs -t lcov --branch --ignore-not-existing --ignore '../*' --ignore "/*" -o ./lcov1.info

The rusult goes well, like this:

TN:
SF:
FN:1,file10::main
FNDA:1,file10::main
FNF:1
FNH:1
BRF:0
BRH:0
DA:1,1
DA:2,1
DA:3,1
LF:3
LH:3
end_of_record

3. But if I add a timeout command like this:

rustc -C instrument-coverage file.rs
timeout 30m ./file
grcov . --binary-path ./file -s ./file.rs -t lcov --branch --ignore-not-existing --ignore '../*' --ignore "/*" -o ./lcov2.info

The coverage result is output like this:

TN:
SF:
FN:1,file10::main
FNDA:1,file10::main
FNF:1
FNH:1
BRF:0
BRH:0
DA:1,1
DA:2,1
DA:3,1
LF:3
LH:3
end_of_record
SF:
FN:1,file10::main
FNDA:1,file10::main
FNF:1
FNH:1
BRF:0
BRH:0
DA:1,1
DA:2,1
DA:3,1
LF:3
LH:3
end_of_record

I don't understand why there are two end_of_record, and the second group of coverage infomation seems to be odd.
Is this a bug of rustc or grcov? Or is there something wrong with the way I'm doing it that causes the results to be incorrect?